void boundaryFill4 (int x, int y, int fillColor, int borderColor)
{
int interiorColor;  

/* Set current color to fillColor, then perform following oprations. */
	getPixel (x, y, interiorColor);
	if ((interiorColor != borderColor) && (interiorColor != fillColor)) 
	{
		setPixel (x, y);    			// Set color of pixel to fillColor.  
		boundaryFill4 (x + 1, y , fillColor, borderColor);
		boundaryFill4 (x - 1, y , fillColor, borderColor);
		boundaryFill4 (x , y + 1, fillColor, borderColor);
		 boundaryFill4 (x , y - 1, fillColor, borderColor)
	}
}